Effect of grain screenings on performance of broiler chickens

The effect of grain screenings in the diet on chicken performance, carcass composition and mass of meat and organs has been determined. The grain screenings contained 44.4% seeds of 25 weeds genera: among others, Sinapis arvensis, Vicia cracca, Rhininnanthus sp.,Tripleurospermium inodorum, Thlaspi arvense, Consolida regalis, Senecio vulgaris, Agrostemna githago, Galeopsis sp. Galium sp. and Echinochloa crus-galli. Screenings were ground, stored for 45 days and added at levels of 0, 3, 6 and 9% to the broiler diet base. Microbiological estimation and coumarine content of screenings was investigated. 160 day-old Ross chicks were allocated to 4 groups with 5 subgroups (replications) of 8 chicks each. Screenings were substituted by barley (w/w). Diet contamination with fungi increased (from 7500 cfu in 0% group to 50000 cfu in 1 g at 9%) with each increment of screening added, while germ content decreased from 3.4 to 1.5 x 10(5) cfu. Grain screening contained low level 0.750 mg x 100(-1)g of coumarin and Gallium aparine seeds 3.3 mg x 100(-1)g. In the first period of feeding, conversion of feed was decreased in chickens on a diet containing 9% screenings. In the second period and for the entire period of the experiment the detrimental effect of 9% screenings on weight gain and feed conversion was significant. Grain screenings supplementation to the diet did not change the dressing percentage and mass of breast, abdominal fat, gizzard, liver, bursa Fabrici proportion in the carcass and activity of serum asparagine aminotransferase. Increasing levels of grain screenings in the diet caused a significant enlargement of the spleen. It can be calculated that in the starter period a content of 2.4% of weed seeds in dietary grain components may cause only,a small decrease, but 7.1% content gave a significant decrease of broiler performance. Results indicated that the level of weed seeds (ground and stored) in the diet for broiler chickens should not exceed 1.33% in the first and 2.7% in the second rearing period.